Gabe over at Penny Arcade has been playing the beta and put up a big post with some of his thoughts today. It's here, just scroll down a bit. My favorite bit:

Turning the quests into an interactive experience makes me care a lot more about them. A quest is still a chance to get XP, money and loot but it’s also an opportunity to advance your character towards the dark or light side based on your decisions. In most MMO’s taking quests is what you do so that you can go play. In SW:TOR, taking quests is playing.